The present invention is directed to migration imaging members. More specifically, the present invention is directed to a migration imaging member comprising a first conductive layer and a conductive overlayer and, situated between the first conductive layer and the conductive overlayer, at least one additional layer, wherein at least one layer situated between the first conductive layer and the conductive overlayer is a layer of softenable material containing migration marking material, and wherein at least one layer situated between the first conductive layer and the conductive overlayer contains a charge transport material. In one embodiment, the conductive overlayer is present on the surface of the imaging member in separate, distinct areas or frames. A specific embodiment of the invention is directed to migration imaging members comprising a first conductive layer, a layer of softenable material containing a charge transport material and migration marking material, and a conductive overlayer on the surface of the imaging member spaced from the first conductive layer, said imaging members having the capability of being imaged by application of voltage between the first conductive layer and the conductive overlayer while the imaging member is exposed to incident radiation, such as light, in an imagewise pattern. In another embodiment, the charge transport material is contained in a charge blocking layer situated between the softenable layer and the conductive overlayer instead of being contained in the softenable layer. Other embodiments of the present invention are directed to apparatuses and processes for preparing the imaging members of the present invention. Still other embodiments of the present invention are directed to apparatuses and processes for using the imaging members of the present invention.
Migration imaging members are well known, and are described in detail in, for example, U.S. Pat. No. 3,975,195 (Goffe), U.S. Pat. No. 3,909,262 (Goffe et al.), U.S. Pat. No. 4,536,457 (Tam), U.S. Pat. No. 4,536,458 (Ng), U.S. Pat. No. 4,013,462 (Goffe et al.), and Migration Imaging Mechanisms, Exploitation, and Future Prospects of Unique Photographic Technologies, XDM and AMEN, P. S. Vincett, G. J. Kovacs, M. C. Tam, A. L. Pundsack, and P. H. Soden, Journal of Imaging Science 30 (4) July/August, pp. 183-191 (1986), the disclosures of each of which are totally incorporated herein by reference. Migration imaging members containing charge transport materials in the softenable layer are also known, and are disclosed, for example, in U.S. Pat. Nos. 4,536,457 (Tam) and 4,536,458 (Ng).
Further, U.S. Pat. No. 4,883,731 (Tam et al.), the disclosure of which is totally incorporated by reference, discloses a xeroprinting process wherein the xeroprinting master is a developed migration imaging member wherein a charge transport material is present in the softenable layer. According to the teachings of this patent, the xeroprinting process entails uniformly charging the master to a polarity the same as the polarity of charges which the charge transport material is capable of transporting, followed by flood exposure of the master to form a latent image, development of the latent image with a toner, and transfer of the developed image to a receiving member.
U.S. Pat. No. 4,880,715 (Tam et al.), the disclosure of which is totally incorporated by reference, discloses a xeroprinting process wherein the xeroprinting master is a developed migration imaging member wherein a charge transport material is present in the softenable layer and non-exposed marking material in the softenable layer is caused to agglomerate and coalesce. According to the teachings of this patent, the xeroprinting process entails uniformly charging the master to a polarity the same as the polarity of charges which the charge transport material is capable of transporting, followed by flood exposure of the master to form a latent image, development of the latent image with a toner, and transfer of the developed image to a receiving member.
U.S. Pat. No. 4,853,307 (Tam et al.), the disclosure of which is totally incorporated herein by reference, discloses a migration imaging member containing a copolymer of styrene and ethyl acrylate in at least one layer adjacent to the substrate. When developed, the imaging member can be used as a xeroprinting master. According to the teachings of this patent, the xeroprinting process entails uniformly charging the master to a polarity the same as the polarity of charges which the charge transport material is capable of transporting, followed by flood exposure of the master to form a latent image, development of the latent image with a toner, and transfer of the developed image to a receiving member.
Migration imaging members with conductive top layers are also known. For example, U.S. Pat. No. 4,081,273 (Goffe), the disclosure of which is totally incorporated herein by reference, discloses a migration imaging system wherein the migration imaging members comprise a first conductive layer, a layer of softenable material, migration marking material, and an overlayer of electrically conductive material which is electrically connected to charge the imaging member electrically. The conductive overlayer can be coated onto the migration imaging member in a continuous fashion, in a semi-continuous pattern such as a Swiss cheese pattern, or in any desired image pattern. Imaging occurs when a potential is applied across the imaging member by a circuit connected to the first conductive layer and the conductive overlayer. Alternatively, the first conductive layer can be contacted to ground and the conductive overlayer can be connected to an electrical potential. Applying potential charges the imaging member with a charge pattern corresponding to the shape of the conductive overlayer. Subsequently, the imaging member is imagewise exposed and developed to cause the migration marking material to migrate through the softenable material.
In addition, U.S. Pat. No. 4,135,926 (Belli), the disclosure of which is totally incorporated herein by reference, discloses a migration layer comprising migration material and softenable material, with the migration layer having a set electrical latent image. The process of setting the electrical latent image comprises providing an imaging member comprising the migration layer, electrically latently imaging the migration layer, and setting the electrical latent image by either storing the migration layer in the dark or applying heat, vapor, or partial solvents in a pre-development softening step. After setting of the electrical latent image, the migration layer can be exposed to activating electromagnetic radiation without loss of the latent image, permitting long delays of up to years between formation of the electrical latent image and the development step that allows selective migration in depth.
Methods of coating panel areas on a web are also known. For example, U.S. Pat. No. 3,349,749 (Utschig), the disclosure of which is totally incorporated herein by reference, discloses a method and apparatus for continuously producing paper having a smooth glossy coating of thermoplastic material such as wax. According to the teachings of this patent, the coating material is applied to the paper by immersing in a bath of melted coating material a cylindrical roll with two circumferentially spaced areas each comprising a multiplicity of closely spaced shallow recesses produced by etching the cylindrical surface of the roll. The two areas are spaced from each other and from each end of the roll by unetched portions of the surface. When the roll is heated, partly immersed in the bath, and rotated, the recesses pick up melted wax and deposit it on one side of the paper when the roll contacts the paper, thereby forming successive wax coats longitudinally spaced from each other. Individual coated sheets can be obtained by cutting the paper between the coatings. Additionally, U.S. Pat. No. 4,264,644 (Schaetti) discloses a method for coating textile bases with a specified pattern of synthetic powder wherein the synthetic powder is applied to a water-cooled engraved roller and transferred to a textile base material while being under heat treatment for a substantial portion of the travel of the textile base along the application roller. Further, U.S. Pat. No. 4,287,846 (Klein) discloses an applicator for depositing a solvent-carried adhesive intermittently along a moving strip. A sump is arranged below the strip to contain a quantity of the solvent, and an adhesive wheel rotates with its lower region immersed in the solvent. The adhesive wheel has a continuous periphery on which adhesive is continuously applied, and an applicator wheel rotates against the adhesive wheel and the bottom of the strip above the sump. The applicator wheel has an intermittent peripheral surface that receives adhesive from the adhesive wheel and applies it in an intermittent pattern to the bottom of the moving strip.
U.S. Pat. No. 3,680,955 (Yata et al.) discloses a camera wherein images are formed electrostatically containing a flexible photosensitive element spaced from a transparent electrode and an electrode roller that brings a narrow width of the flexible photosensitive element into contact with the transparent electrode. The roller is translated across the transparent electrode so that a latent image is formed on the flexible photosensitive element. The apparatus also includes a structure for impressing a D.C. voltage between a transparent electrode and an electrode roller to provide the necessary electrostatic field to transfer the image. Further, U.S. Pat. No. 4,801,956 (Kinoshita et al.) discloses an image recording system capable of storing images at high density wherein a photoelectric conversion member, which converts an optical image into electric image information, is formed in a film configuration. Optical images are incident to a plurality of different regions on the photoelectric conversion member through an optical low-pass filter and a color separation filter to store a plurality of color images. The photoelectric conversion member is made to contact the optical low-pass filter and a scan unit is provided for scanning an electron beam to the photoelectric conversion member.
Although known migration imaging members and imaging apparatuses are suitable for their intended purposes, a need continues to exist for migration imaging members with a first conductive layer and a conductive overlayer that can be sensitized for exposure by applying a voltage between the first conductive layer and the overlayer. A need also exists for migration imaging members capable of forming stable latent images that can be stored for long periods of time prior to development. In addition, there is a need for migration imaging members that can be handled under conditions wherein the members are exposed to light subsequent to formation of a latent image on the member and prior to development of the latent image. There is also a need for migration imaging members that can be charged with reduced energy requirements. Further, there is a need for migration imaging members that enable imaging apparatuses or cameras compatible with the members with reduced bulk and weight. Bulk and weight are generally associated with high voltage power supplies needed to operate corona discharge devices which are conventionally used to sensitize imaging members. In addition, there is a need for migration imaging members with two conductive layers in which some portions of the member can be sensitized to light and imaged independently of other portions of the member. A need also exists for apparatuses and processes for preparing migration imaging members with two conductive layers in which some portions of the member can be sensitized to light and imaged independently of other portions of the member. A further need exists for apparatuses and processes for imaging migration imaging members with two conductive layers in which some portions of the member can be sensitized to light and imaged independently of other portions of the member. There is also a need for migration imaging members with first conductive layers and conductive overlayers wherein the optical contrast density obtained therefrom is substantially improved with respect to known structures, such as those described in U.S. Pat. No. 4,081,273. In addition, there is a need for migration imaging members with first conductive layers and conductive overlayers wherein the conductive overlayers are essentially transparent and contribute no background optical density to the image formed on the member. Further, a need exists for migration imaging members which can be employed in the electronic shutter mode and therefore can be used in apparatuses or cameras which need no mechanical shutter, thereby eliminating bulk.